1. Field of the Invention
The present invention relates to a connection method for probe pins for measurement of characteristics of a thin-film magnetic head and a characteristic measurement method for the thin-film magnetic head.
2. Description of the Related Art
A head gimbal assembly (HGA) constituted by mounting a magnetic head slider on a suspension is usually provided with external connection pads which are electrically connected to a thin-film magnetic head formed on the magnetic head slider.
In the case in which dynamic characteristics of the thin-film magnetic head on the HGA are evaluated, probe pins are brought into contact with the external connection pads to apply a write current to a write magnetic head element and take out a read signal from a read magnetic head element. An IC for head drive, which generates the write current or amplifies the read signal, is connected to the probe pins. Characteristic evaluation of a plurality of HGAs is performed using one IC for head drive in common in this way, whereby it becomes possible to evaluate characteristics of each HGA itself.
At the time of the characteristic evaluation, usually, four probe pins, namely, two probe pins for the write magnetic head element and two probe pins for the read magnetic head element, are connected to four external connection pad.
FIGS. 1 to 3 are perspective views showing conventional examples of a form of connecting probe pins and external connection pads. In these figures, reference numerals 10 and 11, 20 and 21, as well as 30 and 31 denote probe pins for a write magnetic head element; 12 and 13, 22 and 23, as well as 32 and 33 denote probe pins for a read magnetic head element; and 14 to 17, 24 to 27, and 34 to 37 denote external connection pads to which these probe pins 10 to 13, 20 to 23, and 30 to 33 are connected in contact with each other.
As it is evident from these figures, in the related art, the four probe pins 10 to 13, 20 to 23, and 30 to 33 are connected to the external connection pads 14 to 17, 24 to 27, and 34 to 37 in a state in which the probe pins are arranged in parallel with each other.
However, if the probe pins are connected to the external connection pads in a state in which the probe pins are arranged in parallel with each other to perform the characteristic evaluation as in the related art, an extremely large cross talk voltage is applied to the read magnetic head element by a write current flown through the probe pins 10 and 11, 20 and 21, as well as 30 and 31.
In particular, since a recent read magnetic head element has a giant magnetoresistive effect (GMR) laminated structure or a tunnel magnetoresistive effect (TMR) laminated structure, a resistance against an applied voltage is low. When such a large cross talk voltage is applied to the element, it is likely that destruction of the element occurs as in an ESD. Even if this does not lead to complete destruction, it is likely that a resistance change of 1 Ω or less occurs to cause drop or instability of an output voltage.